Abstract:

A rigid axle for a commercial vehicle having individual first and second
suspension struts (1, 2) which define a triangle in a common plane. Each
end of these struts have a joint (3, 4, 5, 6) to connect one end of the
struts to the automotive body (7) and the other end of the struts to the
vehicle axle (8). The end of the struts that is connected to the axle
receives an axial pin (9) for connecting the suspension struts (1, 2) to
the vehicle axle (8).

Claims:

1-11. (canceled)

12. A rigid axle for a commercial vehicle, the axle comprising:individual
two suspension struts (1, 2) that define a triangle in a common plane,
and each end of the two suspension struts (1, 2) having a joint (3, 4, 5,
6) that is connected to one of an automotive body (7) and a vehicle axle
(8) of the commercial vehicle, andan axial pin (9), at least on an axle
side of each of the two suspension struts (1, 2), being inserted in each
of the suspension struts (1, 2) for connecting the suspension struts (1,
2) to the vehicle axle (8).

13. The rigid axle according to claim 12, wherein a point of intersection
(SL) of geometric longitudinal center lines (10) of the two
suspension struts (1, 2), in neutral positions thereof, is located in a
direct vicinity of one of a geometric axle center (MA) and a center
line (11) of the vehicle axle (8).

14. The rigid axle according to claim 12, wherein a point of intersection
(SL) of geometric longitudinal center lines (10) of the two
suspension struts (1, 2), in neutral positions thereof, is located one of
perpendicularly above one of a geometric axle center (MA) and a
center line (11) of the vehicle axle (8).

15. The rigid axle according to claim 12, wherein a center of a joint ball
(MG) of the axial pin (9) of the axial joint (3, 4) of the
suspension struts (1, 2) formed therewith is located in a plane extending
perpendicularly along a geometric center line (11) of the vehicle axle
(8).

16. The rigid axle according to any claim 12, wherein the two suspension
struts (1, 2) defining a geometric triangle with each other together form
an angle (a) between 45.degree. and 60.degree..

17. The rigid axle according to claim 12, wherein the two suspension
struts (1, 2) have either a rod-shaped body or a tubular body (12) that
overall is cast and has a joint housing (13, 14), which is configured on
at least one of the ends thereof.

18. The rigid axle according to claim 17, wherein the axial pin (9) is
directly inserted into parts of the suspension struts (1, 2) configured
as a joint housing (13).

19. The rigid axle according to claim 17, wherein at least one bearing
shell, made of either plastic or metal, is inserted into the joint
housing (13) for receiving a joint ball (15) of the axial pin (9).

20. The rigid axle according to claim 17, wherein at least one damping
element (16), made of an elastomeric material, is inserted into the joint
housing (13).

21. The rigid axle according to claim 17, wherein at least one gliding
layer is present on either the joint housing (13) or on a bearing shell.

22. The rigid axle according to claim 12, wherein the two suspension
struts (1, 2) form a triangular control arm, and longitudinal control
arms (17,18), which deviate from a height position of the two suspension
struts (1, 2) and are fastened to the vehicle axle (8) and the automotive
body (7), are fastened to the vehicle axle (8) by a joint configured as
an axial joint (19, 20).

23. A rigid axle for a commercial vehicle, the axle (8) comprising:first
and second suspension struts (1, 2), each of the first and the second
suspension struts (1, 2) having a longitudinal axis (10), a first end
with a socket housing (13) and an opposed second end with a cylindrical
housing (14);the socket housing (13) of each of the first and the second
suspension struts (1, 2) receiving a ball (15) of a bearing pin (9) for
forming a ball joint (3, 4), the bearing pin (9) of each of the ball
joints (3, 4) being rigidly fixed to a flange (28), which is fixed to the
axle (8);the cylindrical housing (14), of each of the first and the
second suspension struts (1, 2), receiving a connecting pin (34) for
forming an elastomeric joint (5), the connecting pin (34) being rigidly
connected to an automotive chassis (7) having a longitudinal axis; andthe
bearing pin (9) of each of the ball joints (3, 4) are fixed to the
vehicle axle (8) and the connecting pin (34) of each of the elastomeric
joints (5) are connected to the automotive chassis (7) such that the
longitudinal axis (10) of the first suspension strut (1) and the
longitudinal axis (10) of the second suspension strut (2) bisect each
other approximately at a point located directly vertically above an axial
center of the vehicle axle (8) and define a triangle in a common plane.

[0003]Representative rigid axles for commercial vehicles with two
individual suspension struts that in the neutral positions thereof define
a triangle in a common plane, at the ends of which a joint each being
connected to the automotive body and to the vehicle axle, are known, for
example, from DE 43 38 651 A1, DE 101 18 623 A1, or U.S. Pat. No.
5,458,359. In addition, DE 103 48 645 A1 discloses a suspension strut,
which on the one side has an axial joint, the connecting pin of which is
oriented coaxially to the longitudinal center line of the suspension
strut. On the side opposite the axial joint, this suspension strut has a
molecular joint or a molecular bearing. The terms molecular bearing and
molecular joint in this context should be interpreted as being
synonymous. Such molecular joints, or molecular bearings, have a pivot
pin that is supported inside a housing. This pivot pin is surrounded by
an elastomeric body in the housing. A characteristic property of
molecular joints or molecular journals is that they dampen movements that
are introduced via the pivot pin or the suspension strut by means of the
elastomeric body, thereby making the term of molecular bearing an
appropriate one. However, since molecular bearings, or molecular joints,
also enable a relative movements of the components connected to each
other by way of the elastomeric body, they can also be referred to as
molecular joints. The elastomeric body can be connected to the housing
and/or the pivot pin by means of vulcanization. In addition,
configurations are known in which the elastomeric body does not have a
firm adhesive connection to the housing and/or the pivot pin. Such
molecular joints are used in wheel suspensions of a wide variety of motor
vehicles due to their damping and vibration-insulating properties. The
suspension strut disclosed in the published prior art mentioned last is
used as a longitudinal control arm between a vehicle axle of a commercial
vehicle and the automotive body. Moreover the axial joint is fastened to
the automotive body. Axle concepts known so far and used for guiding
rigid axles comprise molecular joints on the axle side, in which the
pivot pins are oriented transversely to the longitudinal center line of
the suspension strut. Such axle concepts, however, require significant
installation space in the region of the vehicle axle. In addition, as a
result of the installation of the molecular joints of the suspension
struts at a distance from the geometric axle center of the rigid axle,
torque is created at the suspension struts, which must be compensated for
during operation. The most frequently used suspension struts additionally
have a molecular joint on either side, which makes the production thereof
overall complex and cost-intensive.

SUMMARY OF THE INVENTION

[0004]The underlying object of the invention is to develop a rigid axle
for a commercial vehicle, the suspension struts of which enable a low
overall height, and which additionally is simple and cost-effective to
produce.

[0005]A rigid axle for a commercial vehicle, comprising two individual
suspension struts that define a triangle in a common plane, at the ends
of which a joint each being connected to the automotive body and to the
vehicle axle, was refined according to the invention in that at least on
the axle side an axial pin is inserted into the suspension struts for
connecting the suspension struts to the vehicle axle.

[0006]The particular advantage of the solution according to the invention
is to be seen in that a smaller installation space is required than was
the case with solutions having molecular joints for connecting the
vehicle axle to the suspension struts. The flanges required for
connecting the suspension struts to the vehicle axle can likewise be
reduced in their overall height. There is even the possibility to
integrate the fastening points for the suspension struts directly in the
vehicle axle. Such a configuration cannot be implemented with molecular
joints. By reducing the overall height in the region of the vehicle axle,
for example, it is possible with the solution according to the invention
to lay the vehicle even lower overall. As a result of the simplification
of suspension struts according to the invention for a rigid axle,
furthermore uniform components and subassemblies can be used for
different applications. In this way, a modular system can be created,
which enables an orientation toward few standard components.
Consequently, in addition to the considerable simplification, a critical
cost advantage also results.

[0007]A first configuration of the invention provides that the point of
intersection of the geometric longitudinal center lines of the suspension
struts in their neutral positions is located in the direct vicinity of
the geometric axle center or the center line of the vehicle axle. Through
such a configuration of the connection of the suspension struts according
to the invention to a rigid axle, interfering torque can be avoided, or
at least significantly reduced, on the components of the suspension when
operating the motor vehicle, which means that the overall mechanical load
of the suspension struts is reduced. In the process, the goal is to
provide the connection of the suspension struts as close as possible to
the axle center or the center line of the vehicle axle, whereby this is
also to be interpreted as an arrangement that is disposed slightly in
front of or behind this intersecting point in the vehicle longitudinal
direction.

[0008]The same advantage as that which was previously mentioned already in
connection with point of intersection of the geometric longitudinal
center lines can be achieved if the point of intersection of the
geometric longitudinal center lines of the suspension struts in the
neutral positions thereof is located perpendicularly above the geometric
axle center or the center line of the vehicle axle. These constructions
mentioned above in each case bring the design position of the suspension
struts, and particularly the attachment of their axle-side joints, as
close as possible to the axle center or the center line of the vehicle
axle.

[0009]According to another construction variant of the invention, the
center of the joint ball of the axial pin of the axial joint of the
suspension struts formed therewith is located in a plane extending
perpendicularly through the geometric center line of the vehicle axle. In
such a configuration, it is true that the geometric point of intersection
of the longitudinal center lines of the suspension struts is disposed
behind the rigid axle of the motor vehicle. However this provides the
advantage that a pitching motion, which is to say a pivoting of the
automotive body about the lateral vehicle axis, can be largely prevented
or at least noticeably reduced. A variant construction that is within the
range of this proposed solution may have a slight distance of the center
of the joint ball of the axial pin to the plane extending perpendicularly
through the geometric center line of the vehicle axle.

[0010]Advantageously, the suspension struts defining a geometric triangle
with each other have an angle between 45° and 60°, which
they form together. In this region of the arrangement of the suspension
struts to each other, they form a triangular control arm, which allows
both optimal longitudinal and lateral force support of the rigid axle of
the commercial vehicle. Such axle location saves additional complex
components, such as Panhard rods.

[0011]With regard to a simplification of the axle location of the entire
rigid axle according to the invention for a commercial vehicle, in
keeping with a particularly advantageous refinement of the invention it
is also proposed that the suspension struts have a rod-shaped or tubular
body that overall is cast and has a joint housing, which is configured on
at least one of the ends of the body. The production of such suspension
struts is significantly simplified compared to the known forged
configurations. In addition, such a design according to the invention can
considerably reduce the number of individual components. In a
particularly advantageous manner, a spherical graphite cast is suited for
the casting. In addition to optimum strength, this material also has
lubricating properties, whereby it becomes possible to directly
integrally mold the joint housing or housings on the rod-shaped or
tubular body of the suspension strut.

[0012]In line with this concept, it is also proposed that the axial pins
be directly inserted into the parts of the suspension struts configured
as joint housings. In this way, the axial pins are also directly
supported in the joint housing. Here, the previously mentioned properties
of the spherical graphite cast play a key role, enabling lubrication of
the bearing point to a limited extent. In this way, a very robust and
simply configured support of the axial pin was created, which
additionally is implemented to have extremely low friction.

[0013]Depending on the requirements that are placed on the suspension
struts of the inventive rigid axle, however, it may also be desirable or
necessary to insert at least one bearing shell made of plastic or metal
into the joint housing in order to accommodate a joint ball of the axial
pin.

[0014]Furthermore, it is possible both with the direct support of the
axial pin in the joint housing of the suspension strut, and with the
support of the axial pin inside a bearing shell, to additionally
introduce at least one damping element in the joint housing. This damping
element, which preferably consists of an elastomeric material, such as
rubber, is suited to absorb vibrations of the individual parts of such a
suspension strut, which can move relative to each other.

[0015]Each of the above-described configurations of the support of the
axial pin can furthermore be improved with respect to the friction
properties thereof by a gliding layer, which is provided in the joint
housing or in the bearing shell.

[0016]A further reaching concept of the invention is that the suspension
struts forming a triangular control arm as well as additional
longitudinal control arms (which on the one hand deviate from the height
of the suspension struts and on the other are fastened to the vehicle
axle and the automotive body) are fastened to the vehicle axle by way of
a joint configured as an axial joint. In this way, the principle
according to the invention can not only be applied to the above
configuration of the suspension struts in the spirit of a triangular
control arm arrangement, but it can also be applied to other control arms
for guiding the rigid axle of a commercial vehicle.

[0017]In addition to the above-mentioned configuration comprising one
axial joint each on the suspension strut, solutions in which one axial
joint each is provided on both sides of the suspension struts are also
within the meaning of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]The invention will be described in more detail below based on the
appended figures. The examples of embodiments shown do not represent any
restriction to the illustrated variants, but are only used to explain the
principle of the invention. To this end, identical or similar components
are denoted with the same reference numbers. In order to be able to
illustrate the operating principle according to the invention, the
figures show only highly simplified representative illustrations, in
which components that are not essential for the invention have been
eliminated. However, this does not mean that such components are not
present in a solution according to the invention, wherein:

[0020]FIG. 2: is the view according to the arrow II from FIG. 1 onto the
rigid axle shown in FIG. 1;

[0021]FIG. 3: is a view of the rigid axle according to the arrow III from
FIG. 2, which is to say from the bottom of the vehicle;

[0022]FIG. 4: is a schematically simplified first possible arrangement of
a suspension strut on a rigid axle according to the ivnention;

[0023]FIG. 5: is another possibility of the arrangement of the suspension
strut on a rigid axle according to the invention; and

[0024]FIG. 6: are sections and a cut view of a suspension strut for use in
a rigid axle according to the invention as a component illustration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]The top view illustrated in FIG. 1 of a rigid axle from the top of
the vehicle, shows two suspension struts 1 and 2, which together define a
triangle in a common plane. The suspension struts 1 and 2 each have a
joint at each of the ends thereof. FIG. 1 shows the joints 3 and 4 of the
suspension struts 1 and 2 on the axle side. The opposing joints 5 and 6
of the suspension struts 1 and 2, these joints being mounted on the
automotive body 7, are not shown in this illustration. In this example,
the automotive body 7 is configured as an enclosed frame (chassis). The
axial pins of the joints 3 and 4 of the suspension struts 1 and 2 are
screwed into a flange mounted on the vehicle axle 8. Beneath the vehicle
axle 8, furthermore two longitudinal control arms 17 and 18 are mounted
at a height that deviates from the fastening of the suspension struts 1
and 2, wherein these control arms are connected both the vehicle axle and
to the automotive body 7. A stabilizing bar 21 is provided to compensate
for rolling motions.

[0026]The fastening of the suspension struts 1 and 2 and of the
longitudinal control arms 17 and 18 to the vehicle axle 8, deviating from
one another in terms of height, emerges more distinctly from the
illustration in FIG. 2. In this figure, also an arrow I is shown, which
indicates the view of the rigid axle according to the illustration from
FIG. 1. The axial joint 3 of the suspension strut 1 visible here is
directly screwed into a flange that is fastened on the vehicle axle 8. On
the opposing side of the suspension strut 1, the strut has a molecular
joint 5, which is connected to the automotive body 7. In order to improve
the driving properties of the rigid axle shown in FIG. 2, it also has a
shock absorber 26. Furthermore, a stabilizing bar 21 is guided along
beneath the vehicle 8, which is connected to the automotive body 7 by way
of a connecting control arm 22 and a holder 24. In the embodiment shown,
the longitudinal control arm also has an axial joint 19 beneath the
vehicle axle 8 on the axle side. This axial joint 19 is screwed into a
suitable flange of the vehicle axle 8. On the side opposite the axial
joint 19, the control arm 17 has a molecular joint, which is not
described in more detail.

[0027]The view of the rigid axle from FIG. 3 corresponds to the direction
of the arrow III in FIG. 2. It clarifies again the arrangement of the
stabilizing bar 21. This bar connects the left part, viewed in the
vehicle direction, to the right part of the automotive body 7 configured
as a chassis. The stabilizing bar compensates for distortions of the
axle, as those that occur, for example, when traveling in a curve.

[0028]FIG. 3 further shows the attachment of the longitudinal control arms
17 and 18 by way of an axial joint each 19, or 20, to a flange each of
the vehicle axle 8. Since the longitudinal control arms 17 and 18 are
mounted beneath the vehicle axle 8, and the suspension struts 1 and 2 are
mounted above the vehicle axle 8, the recognizability of the suspension
struts 1 and 2 is restricted in the view from FIG. 3.

[0029]Finally, FIG. 4 shows a first possible arrangement of the suspension
strut 1 on the vehicle axle 8. The suspension strut 1 in this example has
a joint 3, which is configured as an axial joint. On the side opposite
the axial joint 3, the suspension strut 1 has a molecular joint 5. The
axial pin 9 of the axial joint 3 of the suspension strut 1 in the
position shown here, which is not deflected, has a longitudinal center
line, which runs coaxially to the longitudinal center line 10 of the
suspension strut 1. The axial pin 9, however, can also be disposed in the
neutral installation position thereof at an angle with respect to the
longitudinal center line 10.

[0030]The particularity of the attachment of the suspension strut 1 in
FIG. 4 is that fastening the axial pin 9 to a flange 28 of the vehicle
axle 8 is carried out such the extension of the longitudinal center line
10 of the suspension strut above the axle center MA has a point of
intersection SL with the center line 11 of the vehicle axle 8.

[0031]Such fastening of the suspension strut 1 to the vehicle axle 8
achieves the same optimal guidance of the vehicle axle by way of the
suspension struts, as that which is also possible with another variant of
the attachment of the suspension strut 1 to the vehicle axle 8 according
to FIG. 5. Here the suspension strut 1 is fastened to the vehicle axle 8
such that the joint ball center MG of the axial pin 9 configured as
a ball pin 9 directly coincides with the center line 11 of the vehicle
axle 8 and, projected onto a common plane, is located in the direct
vicinity of the geometric axle center MA. The attachment of the
axial pin 9 again is carried out to the flange 28 of the vehicle axle 8.
In FIGS. 4 and 5, an angle α is provided for illustrating the
straddled arrangement of the suspension struts 1 and 2, this angle
preferably ranging between 45° and 60°. In the example of
the embodiment α=50°. For simplification reasons, in the
illustrations according to FIGS. 4 and 5 in each case only one of the two
symmetrically disposed suspension struts 1 and 2 is shown.

[0032]The possible design of a particularly preferred embodiment of a
suspension strut 1 for use in a rigid axle according to the invention is
apparent from FIG. 6. It should be noted that the suspension strut 1
overall is made of a one-piece cast component, whereby spherical graphite
material comes into use. At the ends of the suspension strut 1, joint
housings 13 or 14 are integrally molded on after the rod-shaped body 12.
In this way, the suspension strut 1, comprising the rod-shaped body 12
and the joint housings 13 and 14, can be produced as a single-piece
component in one casting operation. The example of the suspension strut 1
shown in a simplified section view in FIG. 6 allows the design of the
joints 3 and 5 to be explained in more detail. The joint 3 is constructed
as an axial joint. It has an axial pin 9. This axial pin 9, having a
joint ball 15, is inserted with the joint ball 15 directly into a
suitable recess of the joint housing 13 of the suspension strut 1 such
that a bearing shell can be dispensed with. In order to dampen vibrations
and improve the elastic properties, a recess is provided in the joint
housing 13, a damping element 16 being inserted in this recess. In order
to close the housing opening of the joint housing 13, a locking ring 29
is provided, which with the lateral inside surface thereof rests directly
against the joint ball 15 and thereby likewise forms a metal abutment for
the joint ball 15. On the side opposite the joint ball 15, the locking
ring 29 has a shoulder, against which a conversion segment 30 of the
joint housing 13 rests. The deformation of this conversion segment 30 is
carried out after installation of the ball joint components. The locking
ring 29, however, can also be fixed in the housing 13 in a different
manner. A screw assembly should be mentioned here only by way of example.
Furthermore, the locking ring 28 with a groove, which is present on the
lateral outside surface thereof outside the joint housing 13, is used for
the contact of an edge of a bellows seal 31 sealing the inner joint
components. The second edge of the bellows seal 31 rests directly against
the axial pin 9. For fixation purposes and to improve the sealing effect,
both edge sections of the bellows seal 31 are attached to the component
by means of tension rings, which are not described in detail. In order to
connect the axial pin 9 to a connecting flange 28 of the vehicle axle 8,
the axial pin 9 at the end has a connecting thread 32. On the side
opposite the axial joint 3, a molecular joint 5 is provided on the
suspension strut 1. This molecular joint is characterized by a nearly
circular cylindrical housing 14. A through-hole introduced into the joint
housing 14 is inserted into an elastomeric body 33. This elastomeric body
33, which in the present example has multiple layers and is provided with
intermediate layers to improve the support properties, receives a
connecting pin 34, which in this example was configured as a cylinder
pin. The key in the molecular joint shown is that the connecting pin 34
has a longitudinal center line, which runs transversely to the
longitudinal center line 10 of the suspension strut 1, as is
characteristic for molecular joints and the fastening thereof to vehicle
axles, or to the automotive body.